Carburetor



Maid: 31,719.12;v EIC; 9.0@ ml.;

CARBURETOR Filed May 11, '1939 4 vsneets-slmt 1 BY W. Nido/.257-

Q. Q aff ATTORNEY.

March 31, y1942. F1 CMOCK 'E1-AL Y iARBUREToR I F'il'ed May ll, 1939 4Sheets-Sheet 4 ATTORNEY.;

Patented Maa-3i, i942 illtiiE agirait' 2277,93@ ungenaueren Frank c.Macs aantasten/w. rame, senta Bend, Ind., assgnors te Bendix .aviationCor-1' poration, South Bend, 3nd., a corporation et Delaware applicationinayii, isst, seriali no. 272,99@

(ci. esi-ssl 2.1 claims.

This invention relates to carburetors and more particularly to means forsupplying an acceler ating charge of fuel to a carburetor under certainconditions of operation;

In all types of carburetors, including the type .wherein the fuel forordinary operation is injected under pressure, an increase in the rateci air ilow resulting from rapid opening movement of thethrottle doesnot immediately produce a corresponding increase in the rate of fueloiv. r"i'his slight lag in fuel delivery accompanying a suddenfopeningof the throttle results in a temporary leanness of the` mixture. Inorder to overcome this temporary leanness it has beencommon practice'touse a piston type pump directly operable'by the throttle shaft and soarranged that a small amount of extra fuel is mrnediately forced intothe air stream as the throttle is opened.

"Acceleration pumps of this type have several inherent disadvantages,especially when applied to carhuretors of the pressure feed typedisclosed in the copending application of F. C. Mock, Serial Number202,206, iiled ,April i5, i938. In this type oi carburetor the throttleand the accelerationlpump maybe at widely spaced points and mechanicallyconnect them would result in the use oi an extensive system oicooperatingllinnages. VThis is especially hazardous in aircraft usesince any sticking orjamming of the piston or linkage Iloclss thethrottle. kinematic relationship between the throttle and the pump isdiiicult to obtainin the design of some carburetors.

lt is an object oi the invention to provide improved means Whereby thetendency for the mixture ratio to be temporarily lean immediatelyfollowing an opening of the throttle is overcome. v

It is a further object to provide an acceleration pump having greateraccessibility so thaty the pump capacity can be readily adjusted.

A further object is to provide a pressure feed l carburetor havingimproved acceleration characteristics.

Further objects and advantages oi the invention Will be apparent fromthe following descrip= bar and nozzle taken on the line 3-3 in Flgure 2;I

Figure 4 is a sectional View of the acceleration pump taken on the linelll-itin Figure l;

Figure 5 is a sectional vievir of another modi-s I cation of theacceleration pump'.

Figure 6 is a sectional view of another modi-= cation of theacceleration pump; and

Figure 7 is a fragmentary view of the adapter flange depicting alternatearrangements for supplying fuel to the acceleration pump.

Referring more specifically to Figure l, the carburetor proper comprisesan induction' passage lil leading to a supercharger i2 of an internalcombustion engine of any desirable type. The passage i@ is controlled bya throttle lil operable by a rod it extending from the pilots cockpit ordrivers compartment. The operator therefore directly controls the aircharge to the 2o engine While the fuel charge is automatically venturithroat and communicating through pres-n Also, the necessary a fueldischarge bar 3G.

sure conduit 25. with the control unit hereinafter described. Thesecondary venturi 22 is formed.-

With an annular chamber 25 communicating through 2, plurality of tubes2t with the air scoop iB and through pressure conduit 2i with saidcontrol unit.

Posterior to the throttle ll is an adapter section 23 forming a portionof the induction passage l and having a pressure responsive :fueldischarge nozzle indicated generally at 29 which controls the flow offuel from the conduit 32 to An acceleration pump generally referred toat, 3l is also carried Iby the adapter section 2t and as shown is spacedapl proximately 90 from the nozzle 2li. f

Figure 3 is a sectional view of the discharge 55 The control unitcomprises a hollow casing @5, which may be formed from a plurality ofdiecast sections, assembled and-secured together as shown. The interiorof the casing is divided into flve chambers 36, 3i, 33, 39 and lill bythe four flexible diaphragms di, d2, i3 and t4, each of which has itsouterlend clamped between adjacent sections of the casing .to form afluid-tight gasket, and its central portion apertured and se:- cured'toa control rod 65 by means of hubs t6, di and it having ian'gesat theirends which clamp the diaphragms between them and limit :dexure thereofto an annular looped portion between the flanges and the casing, whichpermits vertical movement of the control rod 05. The hubs and diaphragmsare held in assembled relation on the control rod by means of a threadedcap i9 which terminates in a spherical end slidably movable in a recess50 at the upper end of the casing, thus forming a guide bearing for thecontrol rod assembly. A spring 52 in recess 36 yieldingly urges the roddownwardly as shown.

The lower end of the control rod is connected through a doubleball-and-socket universal joint 5i, with a fuel valve 52 of the sleevetype having ports 53 controlling the admission of fuel to the lowerchamber 00. An adjustable stop 35 limits downward movement of thewcontrol rod and valve 52. An annular fuel chamber 50 surrounds thevalve 52, and has an annular groove adapted to register with the ports53. Any commercial fuel pump arranged to deliver fuel at substan-Vtially constant pressure may be used to deliver fuel to the fuel chamber55|. The one shown at 55 is of a rotary type having a fuel inlet 56,fuel outlet 5l and a by-pass channel 58 controlled by a, pressureresponsive valve 59.

The diaphragms used in the control unit are preferably formed ofmaterial such as sill: fabric impregnated with Neoprene or otherarticial rubber compound. Such diaphragme have substantially no inherentresiliency.

In the operation of the device as thus far described, fuel is deliveredat substantiallyconstant pressure` to fuel chamber 50. whence it howsthrough ports 53, the eiective area of which is controlled by the axialmovement of the control rod 05, into the unmetered fuel chamber 20, andthence through a passageway E0 containing metering orifice 6|, into themetered Vfuel chamber 39, and thence through passageway 22l to thedischarge nozzle 29 and discharge bar 30. Unmetered fuel chamber 00 alsocommunicates, through a longitudinal passage 63 in the control rod 45and cap t9, with chamber 36, sothat the pressures in the two chambersare at all times equal,

Chamber 3l communicates through passage.

way 21 with the annular chamber 25 in the secondary venturi and istherefore subjected to the pressure existing in the air scoop I8.Chamber 38 communicates through passageway 24| with the annular chamber23 in the primary venturi` 20 and is therefore subjected to the pressureexisting at the throat of said venturi. The diierential in pressurebetween air scoop and venturi throat is'proportional to the square ofthe rate of air flow. These two pressures acting on 012901 site sides ofdiaphragm 02 create a net force on` the control rod which is alsoproportional to the square of the rate of air ow and is in a. direc--which is proportional to the square of the quantityof fuel flowing. Thefuel pressures in chambers 40 and 39, differing in degree by thepressure drop across the restriction, act on'opposite sides of diaphragm44 and create a net force on As a-result, for any given conditions ofoperation, the control rod assembly and attached valve 52 will move to aposition such that the force created by fuel flow will be maintainedequal to the force created by the air flow. Since these forces arerespectively proportional to the squares of the quantities of fuel andair flow, it is apparent that the square of the fuel flow is maintainedin constant proportion to the square of the air ow and hence the mixtureratio, that is the ratio of the weight of fuel to the weight of air, ismaintained at a. constant value unless a1- tered by extraneous meanssuch. for example, as those disclosed in the copending application of F.C. Mock, Serial Number 202,206.

The` discharge nozzle assembly 29, better shown in Figures 2 and 3,comprises a nozzle body l0, valve 'l2 arranged to seat at 13, cap '-fl,

l a diaphragm 16, and compression Aspring l0, and

the control rod which is proportional to the iof fuel flow increases,thereby opposing the previously mentioned force generated by air ow.

is held securely in place in the adapter section by screws 80, gasket8|, and packing 82.

Fuel under pressure is received from the control unit through conduit32, whence it ows into the annular fuel chamber 8d and through portsinto the chamber 86, where its pressure is exf erted upon diaphragm 7Bto causervalve 'l2 to move oriits seat againstthe action ofthe compressionA spring l0 and thereby allows the fuel to flow throughpassageways `liti, 89 and 90 and to discharge through the orices 92 intothe air o'wing through the inductionpassage l0. Nozzle cap ld canbe-vented through the passageway 92 to either the atmosphere-as shown,or to venturi suction or air scoop pressure to control the fuel deliverypressure characteristic as fully explained in Mock-Partington,application, Serial Number 243,067 iled November 30, 1938. In place ofthe specific discharge bar and nozzle disclosed herein, any of thenozzleA arrangements disclosed in the above mentioned application may beused# l The acceleration pump 3| (see Figure 4) comprises threechambersi-an' inner chamber |02. an intermediate chamber divided intotwo portions |04, |06 by a web |30, andan outer chamber |08. Chamber |08is separated from the intermediate chamber by a diaphragm IIB which hasits outer edge clamped between the pump body sections H2 and H4, andits,y center portion apertured and secured between -the diaphragm cupmember ||6 and a plate by the nut I I cooperating with the threadedbolt-like extension of the spring retaining cup |20. The diaphragm H0 isformed with an annular groove'as indicated at |22 so as to provide arelatively large stroke-diameter ratio for the diaphragm. A passageway|24 connects the chamber |08 with the air conduit ||l at a pointposterior to\ the throttle. The suction transmitted through saidpassageway urges diaphragm l| |0. to the left, in opposition to 'acompression spring |26, against an adJustable stop |28 which is lockedin place bywthe locking nut |29. L

The body member III is provided with an inwardly extending radial flangeor web |30 having a relatively large central-aperture |32 and arrangedto contact the plate Ill to limit movement of the diaphragm H0 to theright. The flange |30- is also provided with a plurality of aperturesIJI to maintain unrestricted communication between the two positions ofthe intermediate chamber.

Chamber |02 is separated from the intermediate chamber by a diaphragmv|40 which has its outer edge clamped, between the pump body secwelded orriveted to the head of bolt |08 and is adapted to engage an annulargroove in a cylindrical cap.v ltlwhich is riveted to the end of the pumpvalve |52. Lateral clearance as well as a slight amount of end wise oraxial clearance is provided between the bifurcated cup |08 and thegrooveof cap .|50 to' permit -a'. free but limited lateral movement of thevalve |52 relative to the diaphragm after assembly, for purpose ofselfalignment. i

The diaphragm U30 can be of formed type since its stroke need only be sufhcient to move the valve |52 a small distance from the seat ii in thepump nozzle body |56. f

The pump nozzle body is threaded into the adapter section 28 at |51 andis provided with a shoulder |58 cooperating vwith a step in the nozzlecap |50 to securely hold said cap against a shoulder |52 in the adaptersection. Gaskets |65 and |65 at shouldersI |50 and |52 prevent anypassage of fuel from the chamber |02 into the i. `conduit |0 except byway of the valve |52'and the flat or uri- When the throttle is-suddenlyopened the vacuuin in chamber |08 is destroyed and springA |25 urgesdiaphragm ||0 to the right, thereby forcing fuel from the chamber |06through the restriction |86 and passageway |80. A pressure is thuscreatedin chamber |04 in excess of that existing in chamber |02. Thisdifference in pressure `\on opposite sides ofdiaphragm |00 Vurges thediaphragm to the right and opensthe pump discharge valve |52. chamber|02 is under 9, pressure at least equiva-v lent to that in the main fuelnozzle conduit, fuel will issue as a jet from the pump discharge oricesH0. After the fuel displaced by diaphragm |80 has been forced throughorifice |86 a condi.

tion of Vpressure equilibrium will be re-established across thediaphragm M0, and the valve |52 will close.

A chamber |08, which will draw the diaphragm M0 seat ist. apertures lesand les in the pump nozzle body |56 afford unrestricted communicationbetween the chamber |02 and the pump valve and seat. f I

The nozzle cap |50 is provided withone o more orifices |10 which canbevaried in size or number and location to respectively control the rateand direction of the acceleration pump fuel delivery.

A compression spring |72 urges the valve |52 and attached diaphragm M0to the left against the valve seat |513. An extension ile from the endof the valve contacts the inner surface of the nozzle cap |60 to limitthe opening movement of the valve.

Chamber |02 is connected` to chamber |0lby the main discharge nozzlesupply conduit'l, as

shown in Figure 2; or may lead to a source -of unmetered fuel such asthe unmetered fuel chamber ci] of. the control unit or the discharge Aagainstthe stop |28 and refill chamber i0@ with fuel drawn .from theconduit V32. Since the fuel flowing from the control unit yintoconduitf32 is metered in proportion to the air flowing through the airconduit, any fuel ow into the acceleration pump-resultsin a decreasedquantity discharged from' the mainfuel nozzle and hence vin a deficiencyof` gasoline discharged into the air stream. The rate of fuel robbing,that is the rate'of 'refilling the pump` chamber, can be controlled byvarying the size of restriction l or by using a restriction in thepassageway|82';' the majority of engines," however, will continue tooperate and no ill? effects are noticed from the "fuel robbing` actionfollowing a closing of the throttle even though the restrictions areomitted.

If the pump orifices We have a. combined area which is relatively largeas compared to the discharge orice of the main fuel nozzle, the pressurein chamber |02 will decrease upon opening of the valve |52 to a valueless thanthe normal fuel nozzle discharge pressure and part of the"metered fuel which would normally be discharged y Conversely, .by`making the pump o rices small and/or increasing the strengthn of Vthepump spring |12 a part of the fuel displaced by .the

pump diaphragm Hc can be forced to discharge through the lmain dischargenozzle. y

conduit 51 of the engine driven fuel pump 55,

as depicted in Figure 7. :The-principle of operation with each of thesearrangements is explained immediately hereinafter. i Operation with fuelsupply from metered fuel Assume that the engine is operating atrelatively light vload withy a partially closed throttle.

The diaphragm H0 will be-urged to the left, in opposition to the spring|25, against the stop |28 by vacuum transmitted to the chamber |08 fromthe mixture conduit l0 posterior to the throttle acting ori one side ofdiaphragm ||0 andby the pressure of the fuelin chamber |06 acting on theother side of the diaphragm. Chambers |02,` |04 and |06 'are filledwithfuelmder -a pressure equal tov that of the fuel in-themetered fuelchamber 39 or main dischargemozzle conduitf?.

`Sincethe pressures acting onopposite'sides of diaphragm |40 are equal,the pump'valv |52 will be held in l.a closedv positionby the spring andfull of.fuel when thevacuum is low. RA'

-portion of the metered fuel 'supply is therefore It is apparent` thatby proper adjustment of the size of orifices |10, pump spring |12, andrestriction |86, the total quantity of -fuel delivered to-` the airstream during the yactive period of' pufnp operation can be apportionedas desired between the main .fuel nozzle and the pump nozzle. It is alsoapparent that the discharge period of the pump can be lengthened or'shortened by making the restriction |86 smaller or larger so LAas tovary the time required to re-establish an tically empty of fuell duringperiods of operation when the vacuum posterior to the uname is high`used vfor filling the bar upon atransfer `from a conditionof high'vacuum'.operation vto one of 1 low vacuum'operation `as'lis*experienced in any Sincethe fuel in.

' phragm 3 I 0.

conduit during the acceleration peripd is thatv quantity which wouldnormally be supplied by the main control unit, together with thequantity displaced by the diaphragm HU.

Operation with fuel supply from u'nmelered fuel If the acceleration pumpsupply conduit |84 communicates with the unmetered fuel chamber 40, fuelat unmetered fuel pressure will be delivered to the orices |10 duringthe entire period that the valve |52 is open'ed in response to adifferential in pressure across the diaphragm |40, created as previouslyexplained. The rate.

of discharge of this acceleration fuel will depend upon the differencein pressure between the fuel pressureV in the unmetered chamber and thepressure in the air conduit and the size of the restriction throughwhich the fuel must ow such as orices |10. The quantity of extra fueldelivered into conduit l0 by this arrangement will depend not only uponthe rate of discharge but also upon the length of time valve |52 remainsopen. The time available for discharge can be varied by adjustment ofthe size of restriction |86 since decreasing or increasing saidrestriction will respectively increase or decrease the time required forpressure equalization across the diaphragm |40. The quantity of extrafuel for acceleration purposes is therefore not dependent upon thevolume displaced by diaphragm H0, and hence large'quantities ofacceleration fuel can be handled with but a very small pump structure, L

Since the pressure in the unmetered fuel chamber varies with the rate ofair and fuel flow, and since the quantity of acceleration fuel deliveredinto the air conduit depends upon the unmetered fuel pressure, it isapparent that the quantity of acceleration fuel will vary somewhat withthe rate of air flow at the time of the acceleration. This variation hasbeen found desirable on certain engines and undesirable on others andmay be eliminated`if desired by the arrangement of Figure 7 in which theacceleration pump receives fuel from the discharge conduit of a constantpressure fuel supply pump.

A modified form of the invention is shown in Figure 5 in which thereference numerals of Figure 4 with the addition of 200 have been usedto designate similar parts.

The pump is composed of the four chambers 302, 304, 306 and 308separated respectively by the diaphragm 340, a solid web 330, andv thedia- Chamber 308 communicates through passageway 324 with theairl'conduit posterior to the throttle. A passageway 402 in the web 330connects chambers 308 and 304 and is provided with a one-way check valve404 to prevent ow of fuel from chamber 306 to chamber 304 and to permitflow in the reverse direction. Chamber 306 is also connected to chamber302 by a passageway 406 which may be provided with a restriction 408.Passageways 382 and 384 connect the chamber 304 with a source of fuelwhich may either be metered or mime# l tered fuel as previouslyexplained in connection opened,- the vacuum in chamber 308 will bedestroyed and spring 326 will urge the diaphragm 3| 0 to the right,thereby forcing the fuel from chamber 306, through passageway 406,restric tion 408 and into chamber 302 where it Will increase thepressure on the right side of diaphragm 340 and open the valve 352,thereby allowing the fuel to discharge into the air conduit. 4

Check valve 404 prevents any of the fuel displaced from chamber 306 bydiaphragm 3|0 during the pump dischargeperiod from entering the chamber304. I1; is apparent that the additional fuel delivered to the airconduit during the acceleration period, irrespective of whether the fuelsource is from metered or unmetered fuel, is merely the volume of fueldisplaced by the diaphragm 3|0, and the entire quantity is dischargedthrough the pump discharge nozzle. The

rate of delivery of the acceleration pump charge can be increased or.decreased by respectively increasing or decreasing the size of therestriction 408. f

Upon a subsequent closing of the throttle the diaphragm 3|0 is drawn tothe `left by the vac- -uumI transmitted to chamber 308 and fuel is is'forced-through passageway 384 to the fuel source and the balancethrough the pump discharge nozzle. The actual apportioning of theacceleration `pump charge between these two available paths of flow canbe accomplished by adjustment of the relative sizes of the restrictions408 and.404'.

In the description of the several embodiments of the invention, theterms upward and downward as well as left" and right have been used forconvenience, but it Will be understood that the control mechanism'may beinverted relative to the carburetor, or the control unit and carburetorinverted relative to the engine, or the engine and all its accessoriesmaybe inverted gas in acrobati-c'flight) without greatly affecting theoperation as above described.

Although the invention has been described with specific reference tocertain embodiments thereof, it should not be inferred that theinvention is limited thereto nor otherwise except in accordance with thefollowing claims.

We claim:

l. In a charge forming device for an internal combustion engine, aninduction passage, a throttle controlling the same. and an accelerationopen said valve upon a sudden rise in pressure in pump comprising apressure chamber connected to said induction passage posterior to thethrottle, a fuel chamber separated from the pressure chamber by adiaphragm, a second fuel chamber connected to said rst fuel chamber by apassageway and to a source of fuel, a third fuel chamber separated fromthe second fuel chamber by a diaphragm, a duct connecting said rst andlthird fuel chambers, a conduit connecting said third fuel chamber withthe induction passage, and ayv'alve attached to said second diaphragmcontrolling said conduit.

2. The invention dened inclaixn 1 together with checkvalve means in saidpassageway to prevent fuel flow in the direction of the fuel source uponfuel chamber reducing movement of said first-named diaphragm. .Y

3; In a charge forming device for an internal combustion" engine, aninduction passage, a throttie controlling said induction passage, and anacceleration pump comprising a pressurechamber connected tosaidzinduction passage posterior to the throttle, a fuel chamberseparated from the pressure chamber by a diaphragm, a secondfuel chamberseparated from said first fuel chamber by a diaphragm, said fuelchambers being adapted to contain fuel under superatmospheric pressure,a passageway connecting said fuel chambers, a

said ,pressure chamber.

6. The invention dened in claim 5 together with yieldingI means urgingsaid valve toward a closed position.

'1. In a charge forming device for an internal combustion engine, aninduction passage, a throttle controlling the same, and an accelerationpump comprising a pressure chamber connected to said induction passageposterior ifo the throttle, a fuel chamber separated from said pressurechamber by a movable wall, yielding means urging said movable wall in adirection to decrease duct for supplying fuel under superatmosphericpressure to said second fuel chamber, a conduit connecting said secondfuel chamber with the induction passage, av valve oper-ably connected tosaid second diaphragm controlling said lastnamed conduit, and a Y springurging the nrst named diaphragm in a direction to decrease the volume ofthe rst na'med fuel chamber whereby a sudden rise in pressuredn thepressure chamber will increase the pressure in the rst named fuel.`

chamber tothereby urge the second diaphragm in a direction to open thevalve.

d. In a charge forming devicevfor an internal lcombustion engine,l aninduction massage, a throttle controlling said induction passage, and anacceleration pump' comprising a pressure chamber connected tosaid'induction passage pos- A terior to the throttle, a secondchamberseparated from the pressure chamber by a movable wall and having anoutlet, resilient' means urging -said wall in a direction to decreasethe size of the second chamber. a fuehchamber separated from said secondchambereby a movable wall and containing fuel under superatmosphericpressure, a passageway connecting said fuel chamber with a source offuel under pressure, a conduit connecting said fuel chamber with theinduction passage, and a valve operably connected to said secthe sizeofsaid fuel chamber, a second fuel chamber having a movable Wall andbeing closed 'to atmosphere to be thereby adapted to contain fuel undersuperatmospheric pressure, a passage-` way interconnecting said fuelchambers, a conduit connectingone of said ffuelchambers Withy saidsecond movable wall to control the ow of fuel through said duct.

8. In a chargv forming device, an induction passage, a throttlecontrolling the same, a source of fuel under pressure, a fuel conduitconnecting said source with the induction passage, a second fuel conduitconnecting said rst fuel conduit at a point at which the fuel pressureis superatmospheric to the induction passage, a valve in saidsecond-named fuel conduit, and means responsive to variations inthepressure in the induction passage posterior to the throttle fortemporarily openingsaid valve to thereby permit fuel undersuperatmospheric pressure to discharge into the induction passagethrough said second fuel conduit, said last mentioned means comprising avariable pressure chamber connected to the induction passage posteriorto the throttle, a second chamber separated from the pressure chamber bya movable wall capable of relatively large displacements, and a secondAmovable wall capaing the valve.

ond-named movable wall controlling said conduit.

5. In a'charge forming device for an internal,

combustion engine, an induction passage, a throttle controlling theinduction passage, and an ac- -cleration pump comprising a pressurechamber connected to said induction passage posterior to the throttlei asecond chamber separated'from the pressure chamber by a movable wall, asecond A movable Wall arranged to'be subjected` to pressures created in'saidsecond/chamber, a pump Y. dischargenozzle in the induction passage,a conf duit leading from a source of fuel under pressure v t to saidnozzle to supply fuel under super-atmospheric pressure thereto, a valvecpnnectedto said second movable' wall-and normally closing said s,'conduit, -and spring means "ux-ging* said first v named movablel wallAin a direction to. increase .the pressure in 'said second chamber tothereby 75 9'. In a charge forming device, an induction passage; athrottle controlling the same, a fuel nozzle discharging into saidinduction passage,- a pressure responsive valve controlling said nozzle,a fuel conduit connecting a source of fuel under pressure with said fuelnozzle, a second fuel con# Y duit connecting the induction passage withsaid first-named fuel conduit anterior to said nozzle, a

normally closed Vvalve in said second fuel conduit,

and means responsive to an increase in the pressure in the inductionpamage posterior to the Y' throttle for temporarilyopening said valvecomprising ajvariable pressure chamber connected to the induction'passage posterior to the throttle, a fuel chamber connected -toreceivefuel from one of said conduits, a movable wall separating said pressureand. fuel chambers and capable of relatively large displacements towvarysubstantially the volume 'of said fuel chamber, a second fuel chamberforming a portion of said second fuel conduit and having Aamovablewallconnectedfto lthe valve, and'means effective upon fuel chamberreducing movement of the rst movable wall fuel chamber to the saidsecond fuel conduit.

for opening said lvalve` by subjectingv the lastl named movable'wall tovfor transmitting 1 ,a fuel regulating means in said duct including ametering restriction,.and an acceleration pump comprising a pumpdischarge nozzle, a conduit connecting said pump discharge nozzle withthe fuel duct posterior to the metering restriction, a valve in saidconduit, a diaphragm attached to said valve, a variable capacity chamberassociated with said conduit and having a movable wall operable in thechamber increasing direction in response to suction in the inductionpassage posterior to the throttle and spring urgedin the chamberreducing direction upon a decrease in said suction, hydraulic meansconnecting said movable wall and said diaphragm to temporarily open thevalve upon chamber reducing movement of the movable wall, and means toapportion between the main fuel nozzle and the pump nozzle the totalfuel flowing through the metering restriction during the period saidvalve is opened.

11. In a charge forming device for an internal combustion engine, aninduction passage, a throttle controlling the same, a fuel nozzledischarging into said induction passage, a fuel duct connecting a sourceof fuel under pressure and the nozzle, regulating means in said ductincluding a metering restriction, a conduit connecting the inductionpassage with the duct posterior to the metering restriction, a valve insaid conduit, a diaphragm attached to said valve, a variable capacitychamber associated with said conduit having a movable wall operable in achamber reducing direction upon increase in the pressure in theinduction passage posterior to the throttle, and

' hydraulic means associated with the movable wall leading from asourceof fuel under pressure to l theinduction passage posterior to thethrottle, and a pressure responsive valve in said duct whereby the fuelin said duct anterior to said valve is maintained under.superatmospheric pressure: the combination therewith of an accelerationpump comprising a pressure chamber connected to said induction passageposterior to the throttle, a second chamber separated from the pressurechamber by a movable'wall. a 'second movable wall arranged to besubjected to pressures created in said second chamber, a valve connectedto said second movable wall to be actuated thereby, and a fuel conduitcontrolled by vsaid yvalve and leading from the fuel d'uct anterior tosaid pressure responsive valve to the induction passage posterior to thethrottle whereby fuel under superatmospheric pressure will be dischargedtherefrom into the induction passage upon a sudden' rise in pressure insaid pressure chamber.

14. In a charge forming device having an induction passage, a throttletherein, a fuel source, a fuel conduit leading from the source and havting a pair o'f branches discharging in the induction passage posteriorto the throttle. a control lll) unit including a valve responsive to therate of air flow through the induction passage for controlling the fuelflow through the conduit, a pressure responsive valve controlling one ofsaid branches, a second valve controlling the other of said branches,and means for actuating said second valve including a pressure chamberconnected to the induction passage posterior to the throttle. a secondchamber separated from the pressure chamber by a movable Wall, and asecond movable Wall arranged to be subjected to pressures created insaid second chamber and connected to said second valve for actuating thesame.

15. In a charge forming device for an internal combustion engine havingan induction passage, Y

a throttle therein, a main fuel nozzle discharging in said inductionpassage posterior to the throt-v tle, and a control unit responsive tothe rate of air flow through the induction passage for supplying fuelunder superatmospheric pressure to said nozzle comprising a fuel conduithaving a metering restriction therein, unmetered and metered fuelchambers in communication with the conduit respectively anterior andposterior to the metering restriction, a fuel control Valve, and movablewall means in said chambers for actuating said valve: in combinationtherewith of an acceleration pump including a fuel duct leading fromsaid fuel conduit at a point a which the fuel pressure issuperatmospheric to the induction passage, a valve in said duct, andmeans responsive to a sudden increase in the pressure in the inductionpassage. posterior to the throttle for temporarily opening said valve;

16. In a charge forming device having an induction passage, a throttletherein, a fuel nozzle discharging fuel into the induction passage, asource of fuel, a fuel conduit connecting said source and the nozzle andhaving a metering restrictiomand a control unit for controlling the flowof fuel to said nozzle in response to the air flow through the inductionpassage and to the fuel flow through the metering restriction: incombination therewith of an acceleration pump comprising a pressurechamber connected to said induction passage posterior to the throttle, afuel chamber separated from said pressure chamber by a movable Wall,yielding means urging said wall in a direction to decrease the size ofthe fuel chamber, a second fuel chamber having a' movable wall, apassageway interconnecting said fuel chambers, a fuel passage connectingone of said fuel chambers with the fuel conduit posterior to themetering restriction, a duct connecting the second fuel chamber with theinduction passage. and Valve means attached to the second movable wallto control the flow of fuel through said duct.

17. The invention dened in claim 16 comprising in addition a one-waycheck valve in said fuel passage.

18. In a charge forming device, an induction passage, a throttlecontrolling the same, and an acceleration pump comprising a pressurechamber connected to the induction passage posterior to the throttle, afuel chamber separated from the pressure chamber by a movable wall, asecond fuel chamber having a movable Wall adapted to be subjected topressures created in said first fuel chamber, a fuel conduit includingat least one of said fuel chambers for conducting fuel under positivepressure from a source to an outlet in the induction passage, and aValve closely adjacent said outlet for controlling the flow of fueltherefrom. said valve being connected to the second named movable wallto be actuated thereby. 19. The invention defined in claim 1.8comprising in addition a check valve in said fuel conduit.

20. 4The invention dened in claim 18 comprising in addition a pair ofrestrictions in said fuel conduit respectively anterior and posterior toa fuel chamber included thereby.

21. In a charge forming device, an induction passage, a throttlecontrolling the same, a fuel nozzle discharging therein, a fuel pump, aconduit connecting the pump and nozzle, a valve for varying the fuelflow through said conduit, means responsive to the rate of air flowthrough the induction passage for controlling said valve, a ductconnecting the conduit with the induction pasconnected to the 'inductionpassage posterior' to the throttle, a second fuel chamber separated-from the pressure chamber by a diaphragm, an

annular groove in said diaphragm to permit substantial displacementsthereof, a spring urging the diaphragm in a direction to decrease thevolsage, a valvein said duct, a fuel chamber in the duct having amovable wall connected to the second named valve, a variable pressurechamber the said second valve upon fuel chamber decreasing movement ofthe diaphragm.

FRANK C..MOCK.

ROBERT W. MOORE.

